Merged 47946 from trunk: Return true in unsetenv case.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@47947 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/unix/utilsunx.cpp

@@ -1066,7 +1066,7 @@ bool wxSetEnv(const wxString& variable, const wxChar *value)
         // don't test unsetenv() return value: it's void on some systems (at
         // least Darwin)
         unsetenv(variable.mb_str());
-        return;
+        return true;
 #else
         value = _T(""); // we can't pass NULL to setenv()
 #endif